I have extracted the "support by operating system" section out of the platform support FAQs:

Version by operating system (QuarkXPress 7 to 2018)
If you are planning to use the following operating system, here are the QuarkXPress versions that have been officially supported (or still are) on it:

Using macOS High Sierra (10.13)? QuarkXPress 2016, 2017 & 2018 are supported on this OS.

Using macOS Mojave (10.14)? QuarkXPress 2018 is supported on this OS.

NB: Though QX2015 is not officially supported on High Sierra, QX2015 seems to run well on High Sierra with one minor cosmetic issues: Some controls are not shown in Save/Export dialogs. They will appear when you click somewhere (e.g. Desktop shortcut in sidebar).

Using Windows 10 (64 bit)? QuarkXPress 2015, 2016, 2017 & 2018 are supported on this OS.(However, please be aware that as Microsoft calls all new versions of Windows now "Windows 10", older versions of QuarkXPress might not run well on newer versions of Windows 10. Check the internal version number of Windows 10 please.)

Please note that QuarkXPress 2018 is the last version to support Windows 7 (64 bit).

And – as written in the other post – "not supported" does not necessarily mean "won't work". It just means that Quark didn't test this combination and will also not help you to make this run, it is up to you. If you need technical support by Quark, please use a supported combination, which has not reached end-of-life.